Shapefile Character Limit

Shapefile has a Character limit of 245 correct? Feature class 400? So given that AGO only imports shapefiles, If I have a text field that has over 245 characters, then it wont show all of the text correct? If I do it as a FC, it will take all the text but once I export as a Shapefile then it loses the characters that are after 245 characters. Reason for the post is that I made a shapefile in desktop and it had over 245 characters and I did not receive any error message when I was populating a field, I then imported to AGO and it was fine, showed all characters. But then I tried to add more features to the shapefile, and tried to add text those features but now its giving me a 245 character error message. Just curious why its doing it now and not before.